The invention relates to a method and apparatus for checking the record quality of printing products, in particular newspapers.
For the production of newspapers and/or journals, customarily text commands are input on an electronic typesetting machine in such a fashion that, in sequence, the addresses for the various successive characters, such as letters, numbers, punctuation marks, etc. are fed in. The typesetting machine, with the aid of the addresses, then calls for its character memory or font memory for each character the corresponding digital information for recording the character, combines the latter in the commanded sequence and, in this fashion, compiles the so-called bit-map (bit-arrangement map) in which the text image is coded in a line-by-line and point-by-point fashion. The individual bit maps of each of the characters stored in the font memory are customarily represented with 34.times.34 bits per 9 p em quad.
In such a bit-map, customarily parts of a newspaper page, in the form of approximately 1000 image point-wide strips, are intermediately stored transversely over the entire page up to a length of approximately 12,000 bits. A newspaper page of approximately 40.times.60 cm is produced through a line-by-line and point-by-point reading-off of the bit map and a line-by-line and point-by-point exposure of a film with e.g. laser light, whereby the value 0 of a bit is interpreted e.g. as "light off" and the value 1 is interpreted as "light on".
Instead of a laser exposure, also laser evaporating apparatus for the direct production of the printing plate, laser copiers for the direct recording of normal paper, or cathode ray tubes can be employed. However, before the printing can take place, the bit map of the newspaper page must be checked both for type setting errors as well as for its typography. In particular, it must be checked for a correct and final arrangement of the lines, the line justification, the articles, and pictures. This so-called "makeup check" (in memory at the time of type printing) up to the present time is possible only by way of the described indirect route via the manufacture of a film or another material image carrier (e.g. a copy on normal paper). This indirect route is burdensome and undesirable on account of the material expense caused thereby. The time loss connected therewith frequently is of even graver consequence in view of the time pressure under which the record check must be completed prior to copy deadline.
Indeed, theoretically it would be conceivable to avoid this expense and time loss if the information from the bit map is directly transmitted to a display screen of a sufficiently great resolution capability. However, this fails due to the fact that display screens with the resolution capability absolutely necessary for this purpose are not available up to the present time. Whereas the normal television display screens can represent 512.times.512=262,124 or approximately 0.26.times.10.sup.6 picture points, the maximum resolution capability which special models of television display screens available today have corresponds to approximately 1000.times.1000 image points without field separation.
A newspaper page customarily has a size of 40.times.60 cm. The text is most frequently recorded with a letter size of 3.4.times.3.4 mm for the em quad, which corresponds to approximately 2.2 mm for the height of the letter "H". If the upper (or lower) 40.times.40 cm of the newspaper page were represented with 1000.times.1000 image points, then, on the em quad in the center, instead of the 34.times.34 bits, available in the original bit map of the newspaper page, only approximately 8.5.times.8.5 bits would be eliminated; i.e. 8.5.times.8.5 black or white picture points. Thus, even with the use of special display screens with the maximum resolution capability obtainable today, the text would still remain illegible.